Fix Keystone.fetch_token method

While removeing deprecated api_info argument of osclients.Client, we
forgot to clean one place. This patch fixes it

Change-Id: Ib69f249ac812b6dfeedfa58444adbc05592e95a9

rally-jobs/keystone-glance-swift.yaml

@@ -1,5 +1,16 @@
 {%- set cirros_image_url = "https://github.com/cirros-dev/cirros/releases/download/0.3.5/cirros-0.3.5-x86_64-disk.img" %}
 ---
+  KeystoneBasic.authenticate_user_and_validate_token:
+    -
+      args: {}
+      runner:
+        type: "constant"
+        times: 20
+        concurrency: 5
+      sla:
+        failure_rate:
+          max: 0
+
   KeystoneBasic.create_user:
     -
       args: {}

rally_openstack/common/services/identity/keystone_common.py

@@ -176,11 +176,11 @@ class KeystoneMixin(object):
 
     def fetch_token(self):
         """Authenticate user token."""
-        cred = self._clients.credential
         aname = "keystone_v%s.fetch_token" % self.version
         with atomic.ActionTimer(self, aname):
-            clients = osclients.Clients(credential=cred,
-                                        api_info=self._clients.api_info)
+            # use another instance of osclients.Clients to avoid usage of
+            # cached keystone session
+            clients = osclients.Clients(credential=self._clients.credential)
             return clients.keystone.auth_ref.auth_token
 
     def validate_token(self, token):

tests/unit/common/services/identity/test_keystone_common.py

@@ -14,6 +14,7 @@
 
 from unittest import mock
 
+from rally_openstack.common import osclients
 from rally_openstack.common import service
 from rally_openstack.common.services.identity import identity
 from rally_openstack.common.services.identity import keystone_common
@@ -265,13 +266,14 @@ class KeystoneMixinTestCase(test.TestCase):
         self.kc.ec2.delete.assert_called_once_with(user_id=user_id,
                                                    access=access)
 
-    @mock.patch("rally_openstack.common.osclients.Clients")
+    @mock.patch("rally_openstack.common.osclients.Clients",
+                spec=osclients.Clients)
     def test_fetch_token(self, mock_clients):
+        mock_clients.return_value = mock.Mock(keystone=mock.Mock())
         expected_token = mock_clients.return_value.keystone.auth_ref.auth_token
         self.assertEqual(expected_token, self.service.fetch_token())
         mock_clients.assert_called_once_with(
-            credential=self.clients.credential,
-            api_info=self.clients.api_info)
+            credential=self.clients.credential)
 
     def test_validate_token(self):
         token = "some_token"